class Solution
{
  public:
    int removeDuplicates(vector<int> &nums)
    {
        if (nums.empty())
            return 0;

        int index = 0;
        for (int i = 1; i < nums.size(); i++)
        {
            if (nums[index] != nums[i])
                 nums[++index] = nums[i];
                    
        }
         return index + 1;
            
    }
};